The hypothesis of secondary traumatization argues that children raised by parents who were traumatized by war, have more mental health problems than other children. Past evidence for this hypothesis is not consistent. This paper re-examines the hypothesis by analyzing a large nationally representative survey of adult children in the Netherlands in 2002–2003 (n = 3,413) with retrospective information on parental trauma caused by the experience of World War II. Using regression models with an elaborate set of controls, it is found that adult children whose parents suffered from World War II, had poorer mental health and experienced more negative life events. About a third of these long-term effects was mediated by the problems traumatized parents had in maintaining secure relationships with their spouse and children when they were raising their children. Echoing this finding, it is found that traumatized parents have poorer relationships with their children when the children are adult.